This is a copy of a student file that I will compile for each student in the class. This should give you an idea of how I want you to email the citations and the summaries of citations. Note how the student submitted his name and date for each assignment.

Name of student

Writing and Presentation for Chemistry

Dr. Schlegel

Paragraph Summary #1

2/17/05

Name of Student

CARBON NANOTUBES AS CHEMICAL SENSORS

8 Seminars attended@2 each = 8 x 1 = 8 8

1st 2 citations submitted@2 each = 2x 1 = 2 2

1st 2 summaries submitted@1 each = 2 x 1 = 2 2

2nd 4 citations submitted@1 each = 4 x 1 = 4 4

2nd 4 summaries submitted@1 each =4 x 1 = 4 4

Poster presentation ...... = 10 7

Poster content ...... = 20 16

Total for seminar portion...... 100 43

Total for writing portion...... 10098

Grand total ...... 150 141

Grade in the course ………………………………………A

Overall good presentation of your poster. I would have liked to have known how scientists were able to distinguish between the three different forms of the carbon nanotubes.

1.Li, J., Y. Lu, Q. Ye, M. Cinke, J. Han, and M. Meyyappan. (2003) Carbon Nanotube Sensors for Gas and Organic Vapor Detection. Nano Letters Vol. 3, No. 7, 929-933

2.Durkop T., S.A. Getty, E. Cobas, and M.S. Fuhrer. (2004) Extraordinary Mobility in Semiconducting Carbon Nanotubes. Nano Letters Vol. 4, No. 1, 35-39

3.Yun, M., Myung, N.V., Vasquez, R.P., Lee, C., Menke, E., and Penner, R.M. (2004) Electronically Grown Wires for Individually Addressable Sensor Arrays. Nano Letters Vol. 4, No. 3, 419-422

4.Chen, R.J., Bangsaruntip, S., Drouvalakis, K.A., Kam, N.W.S., Shim, M., Li, Y., Kim, W., Utz, P.J., and Dai, H. (2003) Noncovalent Functionalization of Carbon Nanotubes for Highly Specific Electronic Biosensors. PNAS Vol. 100, No. 9, 4984-4989

======sent2/19/05

Name of student

Writing and Presentation for Chemistry

Dr. Schlegel

Paragraph Summary #1

2/17/05

A nanomaterial called single-walled carbon nanotubes (SWNTs) is becoming important in biology because of their potential use as biological sensors. One proposed use is for detecting certain proteins that are associated with certain diseases. A specific example is detection of multiclonal antibodies (mAbs) that bind to human U1A, which are believed to be involved with diseases such as systemic lupus erythematosus and mixed connective tissue disease. Using Atomic Force Microscopy (AFM), Quartz Crystal Microbalance (QCM), and electronic transport measurements, it can be shown that proteins exhibit non-specific binding (NSB) to SWNTs. Adding substances such as polyethylene oxide (PEO), Tween 20, and triblock copolymers will prevent proteins from binding to the SWNTs because they are adsorbed to the surface of SWNTs and are “protein blocking”. Binding these substances to SWNTs, however, does not affect the electrical properties of them, but the electrical current produced by the nanotubes is greatly reduced due to the absence of proteins. This fact shows that the SWNTs, not the proteins, that have potential for use as sensors because they give off more electrical current (they “sense”) when the proteins are attached. In order to allow for selective binding of certain proteins to the SWNTs, “binding partners”, or proteins that are attached to allow specific binding, are added to the protein-blocking layer already present. This allows for binding with high specificity to occur. This specificity and the electrical conductance of the SWNTs is promising evidence that SWNTs could be used as biological sensors someday.

Citation:

Chen, R.J., S. Bangsaruntip, K. A. Drouvalakis, N. W. S. Kam, M. Shim, Y. Li, W. Kim, P. J. Utz, and H. Dai. 2003. Noncovalent Functionalization of Carbon Nanotubes for Highly Specific Electronic Biosensors. PNAS 100: 4984-4989

Name of student

2-22-05

Writing and Presentation for Chemistry

Dr. Schlegel

Carbon Nanotube Sensors for Gas and Organic Vapor Detection

Single-walled carbon nanotubes (SWNTs) can detect gases such as nitrogen dioxide (NO2) and ammonia (NH3) at room temperature, unlike metal oxide microfilm sensors, which work at temperatures greater than 350˚C. At room temperature, SWNT sensors have poor sensitivity, but they do function. The sensitivity of SWNTs is accounted for by large changes in electrical conductance of semi-conducting SWNTs induced by charge transfer of gas molecules to them. The problem with using SWNTs lies within the production of the SWNTs because a combination of metallic and semi-conducting SWNTs forms, and metallic SWNTs do not work as sensors. This results in low sensitivity of the sensors. Metal oxide microfilm sensors have better sensitivity, but only function at temperatures greater than 350˚C. Combining these two different types of sensors makes for a better sensor because it can be used in a practical environment. To make the improved sensor, researches combined SWNTs and metal oxide microfilm sensors to make a simple SWNT sensor platform. This increases the sensitivity of the sensors and allows for use at room temperature (or near-room temperature). The detection of molecules other than NO2 and NH3 was also a problem. Using the combination sensors allows for sensing of molecules such as benzene, acetone, and nitrotoluene because the mechanism of sensing is different than each type of sensors’ sensing mechanisms.

Li, J., Y. Lu, Q. Ye M. Cinke, J. Han, and M. Meyyappan. 2003. Carbon Nanotube Sensors for Gas and Organic Vapor Detection. Nano Letters 3: 929-933

Extraordinary Mobility in Semi-conducting Carbon Nanotubes

Mobility is used to determine the conductivity difference per charge. It determines the sensitivity of devices that use semi-conducting nanotubes, such as field-effect transistors or chemical and biochemical sensors. In chemical sensors, mobility is used to detect charge or chemical signal that has been converted to charge. The values that were previously determined range from 20 cm2/Vs to infinity for short instruments that lack Ohmic contacts. With devices containing long (greater than 300 micrometer) ohmically contacted nanotube devices, mobility in semi-conducting nanotubes is about 79,000 cm2/Vs at room temperature and their intrinsic mobility is even greater (>100,000 cm2/Vs). These values are greater than the values for any present semi-conducting device and are promising news for the development of sensors using carbon nanotubes in larger-scale devices.

Durkop, T., S. A. Getty, E. Cobas, and M. S. Fuhrer. 2004. Extraordinary Mobility in Semi-conducting Carbon Nanotubes. Nano Letters 4: 35-39

Electrochemically Grown Wires for Individually Addressable Sensor Arrays

Nanomaterials have been looked at for their potential use as sensors for detecting things proteins, gases, etc. In assembling devices using nanomaterials, problems involving controllability, reproducibility, and operation in large-scale environments have arisen. Electrodepositing materials such as metals, alloys, metal oxides, semi-conductors, and conducting polymers onto nanowires can help reduce the effects of these problems. Using this technique allows for “growing” the wires electrochemically (i.e. making the wires and while being able to control their length and other properties) to help the developer have more control over the nanowires’ sensitivity and the reproducibility of the results.

Yun, M., N. V. Myung, R. P. Vasquez, C. Lee, E. Menke, and R. M. Penner. 2004. Electrochemically Grown Wires for Individually Addressable Sensor Arrays. Nano Letters 4: 419-422

======sent 3/1

Citations #2 for Writing and Presentation for Chemistry

  1. Dai, Y. and K. Shiu. 2004. Glucose Biosensor Based on Multi-Walled Carbon Nanotube Glassy Carbon Electrode. Electroanalysis 16: 1697-1703.
  1. Heirold, C. 2004. From Micro- to Nanosystems: Mechanical Sensors Go Nano. Journal of Micromechanics and Microenginering.14: S1-S11.
  1. Chen, R.J., H. C. Choi, S. Bangsaruntip, E. Yenilmez, X. Tang, Q. Wang, Y. Chang, and H. Dai. 2004. An Investigation of the Mechanisms of Electronic Sensing of Protein Adsorption on Carbon Nanotube Devices. JACS 126: 1563-1568.
  1. Sotiropoulou, S. V. Gavalas, V. Vamvakaki, and V. A. Chaniotakis. 2003. Novel Carbon Materials in Biosensor Systems. Biosensors and Bioelectronics 18: 211-215.

======sent 3/5

Name of student

Writing and Presentation for Chemistry

3/6/05

Dr. Schlegel

Second Set of Paragraph Summaries for Writing and Presentation for Chemistry

Dai, Y. and K. Shiu. 2004. Glucose Biosensor Based on Multi-Walled Carbon Nanotube Glassy Carbon Electrode. Electroanalysis 16: 1697-1703.

  1. A biological sensor is in the works that detects glucose. This sensor uses multi-walled carbon nanotubes (MWNTs) and a glucose oxidase electrode to sense glucose. To measure the effects of glucose binding to these sensors, electrochemistry was involved using an electrochemical analyzer, which contained a silver/silver chloride reference electrode. In the experiment, oxygen was dissolved on the electrode and acted as a catalyst for glucose binding to the electrode as part of the “sensing”. Oxygen binds less to electrodes without MWNTs attached, so putting the MWNTs on the electrodes, increases the oxygen binding, which, in turn, increases glucose binding. Potential differences were then measured when adding glucose from the zero point. Current was found to top-out when the MWNTs loading was higher than 280 μg/cm2. The sensitivity of the sensor at this concentration for glucose seems to be the best. Biologically common species were also added to see if they would interfere with the signal response. When using a negative zero point potential, none of the species introduced interfered with the signal response.

Heirold, C. 2004. From Micro- to Nanosystems: Mechanical Sensors Go Nano. Journal of Micromechanics and Microenginering.14: S1-S11.

  1. Miniaturization is something that is always a topic of discussion, especially in electronics. It is important for many different reasons: smaller size can be important in application, it usually results in using less energy, it can be more cost-effective, and carbon nanotubes are a very strong material. Nanomaterials such as carbon nanotubes are being looked at for use in sensors because they fulfill all of these qualifications and can even be more sensitive as sensors than microsystems. A problem that has arisen in using CNTs in sensors is reproducing the CNTs so that their sensitivity is the same. Right now, using CNTs as sensors seems to be an idea that is in its initial stage of research and is not something that is being used as of yet. One idea to circumvent this problem is to use CNTs and micromaterials as a sensor.

Chen, R.J., H. C. Choi, S. Bangsaruntip, E. Yenilmez, X. Tang, Q. Wang, Y. Chang, and H. Dai. 2004. An Investigation of the Mechanisms of Electronic Sensing of Protein Adsorption on Carbon Nanotube Devices. JACS 126: 1563-1568.

  1. This article describes a possible mechanism for how adsorption of proteins leads to a change in current in a carbon nanotube. One thought for a mechanism of how protein adsorption causes electrical conductance to change in a carbon nanotube is that when proteins are adsorbed to a CNT surface the proteins exert a charge transfer, which causes the change in conductance. Another proposed mechanism, which is discussed in this article, is that the metal-nanotube boundary in a sensor causes the change because the nanotube’s electrical properties are changed when the proteins are adsorbed and a reduction of the work function of the metal is thought to occur. To support this mechanism, these researchers added proteins to three different types of sensors. One was a bare nanotube-metal based sensor that allowed proteins to be adsorbed to both the nanotube and the metal (Pd or Pd/Au) electrode. A second device allowed for adsorption on the CNTs and not the electrode by coating the electrodes with methoxy(poly(ethylene glycol))thiol (mPEG-SH), which prevents protein binding. A third device was coated with mPEG-SH on both the electrode and the CNT. By adding the same proteins to each type of sensor the group showed that a change in conductance of a nanotube based sensor is mostly due to the metal-nanotube contact region.

Sotiropoulou, S. V. Gavalas, V. Vamvakaki, and V. A. Chaniotakis. 2003. Novel Carbon Materials in Biosensor Systems. Biosensors and Bioelectronics 18: 211-215.

  1. Many different materials are made from carbon are being used towards developing a biosensor, such as porous carbon, fullerenes, and carbon nanotubes. In this article, the authors discuss using fullerenes and carbon nanotubes in their experiment, but other experiments have showed that nanotubes can be used in biosensors. This experiment shows how fullerenes, in addition to other carbon materials, can be used in biosensors. The group developed two glucose biosensors. One used porous carbon and the other used fullerenes. They showed that both will sense the glucose, but the fullerene-based sensor was better at detecting the glucose than the porous carbon.